When Samuel Coleridge wrote, “Water, water everywhere and not a drop to drink” in his epic poem “The Rime of the Ancient Mariner,” he was affirming what we all know: Water is pretty important, and it’s a scarce resource. In the same way that water was a scarce, life-giving resource for the 18th century sailors in Coleridge’s poem, water is a precious resource for the operations of most data centers. As our industry focuses more on sustainability, we should respect that scarcity of this resource by using water more wisely.
This should be a core principle of data center sustainability. After all, sustainability is about more than just green power. Although data center water usage has always been a consideration within the sustainability equation, the consumption of water by data centers using water-based cooling is under increasing scrutiny due to the increasing size of today’s hyperscale locations. To better understand the issue, let’s look at how much H2O the average water-based cooling data center actually uses. It’s estimated the average 1-MW data center uses 7 million gallons of water annually, and usage only increases with size, as a 15-MW facility is estimated to use approximately 131 million gallons annually. No matter how you look at it, that’s a lot of water.
This is part of an overall socioeconomic trend of rising water usage. Global water use has increased sixfold over the past 100 years, as our economy has grown. That growth trend will continue, with water consumption expected to continue to increase by 1% every year, according to the United Nations Educational, Scientific, and Cultural Organization. As water becomes increasingly scarce, more attention will continue to be aimed at developing less water intensive cooling alternatives for data centers.
While water usage has always been a consideration for data center operators (for example, the water usage effectiveness [WUE] standard), multiple factors are converging to increase the need to make water conservation a bigger focus in our industry.
- It’s not an infinite resource. Although water comprises 70% of the world’s surface, only a small percentage is easily accessible or usable. The UN encourages countries and regions to be proactive in treating water as a scarce resource.
- Data center use and performance requirements are rapidly becoming the equivalent of public utilities where ubiquitous availability is the expected norm.
- The demand for compute and storage functionality will only be exacerbated in a post-COVID world. Keeping up with accelerating data center capacity requirements will continue to result in larger facilities across the globe. Since it takes roughly 7 million gallons of water to cool a single megawatt, the potential water requirements for the cooling systems of these multi-megawatt behemoths will be measured in the billions of gallons annually.
- The simple concept of supply and demand will continue to increase cooling costs without the incorporation of less water-intensive alternatives.
- The movement toward more efficient data center water usage is generating a variety of alternative strategies. For example, some hyperscale facilities are starting to include their own on-site water treatment facilities to tap into local, non-potable water sources. Others are incorporating rainwater recovery strategies to capture rain, store it on-site and use it for cooling to reduce the burden on local water supplies.
- At Compass Datacenters, we’re eliminating the need for water-based solutions through the use of airside cooling. Free, 100% renewable air is drawn into the facility through finely calibrated filters (to remove particulates) and used to cool the facility. While certain areas of the country have more “free cooling” hours than others, there is virtually nowhere in the country where it can’t be used. Even Houston provides more than 3,600 hours of free cooling annually.
- The pivot toward more water-friendly solutions comes as water availability is a major concern in the context of climate change. Mindful of the fact that data centers have a 10- to 15-year lifespan, more and more operators want to know they will not be putting pressure on local water supplies and potentially be forced to retrofit at great cost.
- The near future is expected to offer the largest level of data center demand the industry has experienced to date. The enhanced cooling needs of the resulting ever-growing facilities, coupled with the issues surrounding water availability and usage, will continue to drive innovations in water usage within data centers to help preserve a precious resource. I think Coleridge would agree this is a good thing.